The design of an effective user interface poses many challenges. One challenge is how to provide a user with an optimal amount of visual information or functionality, given the space limitations of a display and the needs of a particular user. This challenge can be especially acute for devices with small displays, such as smartphones or other mobile computing devices, because there is often more information available to a user performing a particular activity (e.g., browsing for audio or video files in a library of files) than can fit on the display.
Although there have been a variety of advances in user interfaces, there remains room for improvement.